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71 lines
2.5 KiB
71 lines
2.5 KiB
4 years ago
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# reflect2
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[](https://sourcegraph.com/github.com/modern-go/reflect2?badge)
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[](http://godoc.org/github.com/modern-go/reflect2)
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[](https://travis-ci.org/modern-go/reflect2)
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[](https://codecov.io/gh/modern-go/reflect2)
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[](https://goreportcard.com/report/github.com/modern-go/reflect2)
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[](https://raw.githubusercontent.com/modern-go/reflect2/master/LICENSE)
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reflect api that avoids runtime reflect.Value cost
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* reflect get/set interface{}, with type checking
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* reflect get/set unsafe.Pointer, without type checking
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* `reflect2.TypeByName` works like `Class.forName` found in java
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[json-iterator](https://github.com/json-iterator/go) use this package to save runtime dispatching cost.
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This package is designed for low level libraries to optimize reflection performance.
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General application should still use reflect standard library.
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# reflect2.TypeByName
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```go
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// given package is github.com/your/awesome-package
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type MyStruct struct {
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// ...
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}
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// will return the type
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reflect2.TypeByName("awesome-package.MyStruct")
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// however, if the type has not been used
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// it will be eliminated by compiler, so we can not get it in runtime
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```
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# reflect2 get/set interface{}
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```go
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valType := reflect2.TypeOf(1)
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i := 1
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j := 10
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valType.Set(&i, &j)
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// i will be 10
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```
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to get set `type`, always use its pointer `*type`
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# reflect2 get/set unsafe.Pointer
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```go
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valType := reflect2.TypeOf(1)
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i := 1
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j := 10
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valType.UnsafeSet(unsafe.Pointer(&i), unsafe.Pointer(&j))
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// i will be 10
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```
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to get set `type`, always use its pointer `*type`
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# benchmark
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Benchmark is not necessary for this package. It does nothing actually.
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As it is just a thin wrapper to make go runtime public.
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Both `reflect2` and `reflect` call same function
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provided by `runtime` package exposed by go language.
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# unsafe safety
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Instead of casting `[]byte` to `sliceHeader` in your application using unsafe.
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We can use reflect2 instead. This way, if `sliceHeader` changes in the future,
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only reflect2 need to be upgraded.
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reflect2 tries its best to keep the implementation same as reflect (by testing).
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